[CLEANUP] Use Preg::split to handle unexpected preg_split errors (#1314)

This resolves three PHPStan errors.

Instances of calls to `preg_split` in the two (identical)
`parseCssDeclarationsBlock` methods are not updated - those are covered
separately by #1311.

phpstan-baseline.neon

@@ -7,7 +7,7 @@ parameters:
 
 		-
 			message: "#^Argument of an invalid type array\\<int, string\\>\\|false supplied for foreach, only iterables are supported\\.$#"
-			count: 2
+			count: 1
 			path: src/CssInliner.php
 
 		-
@@ -25,11 +25,6 @@ parameters:
 			count: 2
 			path: src/CssInliner.php
 
-		-
-			message: "#^Parameter \\#2 \\$array of function array_map expects array, array\\<int, string\\>\\|false given\\.$#"
-			count: 1
-			path: src/CssInliner.php
-
 		-
 			message: "#^Only booleans are allowed in an if condition, int\\|false given\\.$#"
 			count: 1
@@ -85,11 +80,6 @@ parameters:
 			count: 1
 			path: src/HtmlProcessor/HtmlPruner.php
 
-		-
-			message: "#^Parameter \\#1 \\$array of method Pelago\\\\Emogrifier\\\\Utilities\\\\ArrayIntersector\\:\\:intersectWith\\(\\) expects array\\<\\(int\\|string\\)\\>, array\\<int, string\\>\\|false given\\.$#"
-			count: 1
-			path: src/HtmlProcessor/HtmlPruner.php
-
 		-
 			message: "#^Parameter \\#1 \\$elements of method Pelago\\\\Emogrifier\\\\HtmlProcessor\\\\HtmlPruner\\:\\:removeClassAttributeFromElements\\(\\) expects DOMNodeList, DOMNodeList\\<DOMNode\\>\\|false given\\.$#"
 			count: 1

src/CssInliner.php

@@ -693,7 +693,8 @@ private function hasUnsupportedPseudoClass(string $selector): bool
             return false;
         }
 
-        foreach (\preg_split('/' . self::COMBINATOR_MATCHER . '/', $selector) as $selectorPart) {
+        $preg = (new Preg())->throwExceptions($this->debug);
+        foreach ($preg->split('/' . self::COMBINATOR_MATCHER . '/', $selector) as $selectorPart) {
             if ($this->selectorPartHasUnsupportedOfTypePseudoClass($selectorPart)) {
                 return true;
             }
@@ -1053,7 +1054,7 @@ function (array $matches): string {
             function (string $selectorPart): string {
                 return $this->removeUnsupportedOfTypePseudoClasses($selectorPart);
             },
-            \preg_split(
+            (new Preg())->throwExceptions($this->debug)->split(
                 '/(' . self::COMBINATOR_MATCHER . ')/',
                 $selectorWithoutUnmatchablePseudoComponents,
                 -1,

src/HtmlProcessor/CssToAttributeConverter.php

@@ -291,8 +291,7 @@ private function isTableOrImageNode(\DOMElement $node): bool
      */
     private function parseCssShorthandValue(string $value): array
     {
-        /** @var array<int, string> $values */
-        $values = \preg_split('/\\s+/', $value);
+        $values = (new Preg())->split('/\\s+/', $value);
 
         $css = [];
         $css['top'] = $values[0];

src/HtmlProcessor/HtmlPruner.php

@@ -6,6 +6,7 @@
 
 use Pelago\Emogrifier\CssInliner;
 use Pelago\Emogrifier\Utilities\ArrayIntersector;
+use Pelago\Emogrifier\Utilities\Preg;
 
 /**
  * This class can remove things from HTML.
@@ -84,9 +85,10 @@ private function removeClassesFromElements(\DOMNodeList $elements, array $classe
     {
         $classesToKeepIntersector = new ArrayIntersector($classesToKeep);
 
+        $preg = new Preg();
         /** @var \DOMElement $element */
         foreach ($elements as $element) {
-            $elementClasses = \preg_split('/\\s++/', \trim($element->getAttribute('class')));
+            $elementClasses = $preg->split('/\\s++/', \trim($element->getAttribute('class')));
             $elementClassesToKeep = $classesToKeepIntersector->intersectWith($elementClasses);
             if ($elementClassesToKeep !== []) {
                 $element->setAttribute('class', \implode(' ', $elementClassesToKeep));